1. Field of the Invention
The present invention relates to a means for extracting a photographic subject from still image data, and more particularly to a face detecting apparatus and method.
2. Related Background Art
Digital still cameras and digital video cameras are prevailing rapidly nowadays. Along with this, there are increasing demands for tools such as a tool for processing images photographed with these photographing apparatuses to provide a high image quality.
In the high image quality process, for example, a face detection process is executed for an image, and if there is a human face, a correction amount is determined basing upon the detected face. This method is widely known.
Most of the process time required for the high image quality process is occupied by the face detection process time. This process time has been long desired to be shortened.
Several means for improving a face detection efficiency have been proposed.
For example, Japanese Patent Application Laid-Open No. 2003-163827 (no corresponding U.S. application) proposes an approach by which a photographing apparatus executes a pixel thinning process for a whole image in accordance with a photographing mode and a photographic subject magnification factor, and changes the number of divided blocks to be subjected to the face detection process. With this approach, a face detection precision is changed for each photographed image to improve the process efficiency.
According to the invention described in Japanese Patent Application Laid-Open No. 2003-163827, the face detection process is executed for the whole area of an image. There arises therefore the problem that an area subjected to the face detection process increases greatly as the image data amount increases, and the process time prolongs. Another problem resides in that the detection precision is degraded if the number of thinned pixels is increased in order to shorten the process time.